Methoxyphenolic Compounds Research Articles

Catalytic mechanism of N-containing biochar on volatile-biochar interaction for the same origin pyrolysis

Nitrogen, as a common element, is widely present in biomass. The effects of nitrogenous substances on the same origin pyrolysis of biomass and the consequences of N-containing biochar on the catalytic process of volatiles are important for further analyzing the pyrolysis mechanism of biomass. In this research, N-containing biochar was prepared under different conditions, and the interaction between N-containing biochar and biomass pyrolysis volatiles at 400–700 °C was studied. The results show that N-containing biochar can simultaneously participate in reactions as adsorbents, catalysts, and reactants. Its catalytic effect is obviously different for various N configurations. Pyridinic N and pyrrolic N can promote the cracking of lignin into methoxy phenol compounds and promote the further cracking of 5-hydroxymethylfurfural. Graphitic N and oxidized N can promote the further decomposition of phenol and the conversion of D-xylose into small-molecule ketones. In addition, oxidized N can also inhibit the cracking of lignin to produce guaiacol. In the long-term interaction, the highly active pyridinic N tends to convert to a more stable graphitic N.

Effect of main taste compounds on the release of methoxyphenolic compounds in Pu-erh tea

As a typical Chinese tea, Pu-erh tea attracts much attention due to its unique flavor formed by taste and aroma compounds. To study the effects of taste compounds on the aroma release, model solutions containing five typical methoxyphenolic compounds (MCs) and main taste compounds with different concentrations were prepared based on the analysis of Pu-erh tea samples. GC-MS results indicated that the release of five MCs was inhibited by theabrownin, tea polysaccharide, tea polyphenol and catechins. The release of 1,2-dimethoxybenzene, 3,4-dimethoxytoluene and 1,2,3-trimethoxy-5-methyl-benzene was promoted by gallic acid under a low concentration (≤4 mg/g). Statistically, gallic acid had the most significant effect on the release of MCs. Isothermal titration calorimetry suggested that hydrogen bonds and hydrophobic effects had potential contributions to the interaction between taste and aroma compounds. This work will provide the research basis for revealing the formation mechanism of tea flavor.

Calcium oxide derived from eggshells supported on titanium oxide green catalysts for lignin hydrogenolysis under supercritical alcohol solvents

Catalytic depolymerization of lignin has been investigated in the presence of egg shell derived CaO/TiO2 catalysts. Reaction was carried out for different reaction temperatures (250, 280 and 310 °C) at different reaction holding time at presence of N2 and H2 gas under ethanol, methanol and water solvent. Highest bio-oil yield was found with CaO/TiO2-800 catalyst in ethanol solvent under N2 (74.8 wt%), and H2 (82.8 wt%) environment compared to the water solvent. Under hydrogen environment very less amount of unreacted residue was produced. Bio-oil analysis showed that in under nitrogen environment catalytic depolymerization of lignin produced alkyl phenolic monomer compounds 68.0% with methoxy phenolic compounds 24.0%. Interestingly hydrogen promoted the deoxygenating and hydrogenation reaction which produced higher cyclohexane compounds 38.2% and aromatic hydrocarbon 19%. This is suggesting that the effectively breaking of β-O-4 bond by the catalysts which has an excellence character for the industrial application. Elemental analysis shows that hydrogen enhanced the bio-oil quality compared to the nitrogen environment. This work introduces new perspectives for the efficient production of functional compounds from lignin assisted by egg shell derived green catalysts.

Natural Methoxyphenol Compounds: Antimicrobial Activity against Foodborne Pathogens and Food Spoilage Bacteria, and Role in Antioxidant Processes.

The antibacterial and antioxidant activities of three methoxyphenol phytometabolites, eugenol, capsaicin, and vanillin, were determined. The in vitro antimicrobial potential was tested on three common foodborne pathogens (Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus) and three food spoilage bacteria (Shewanella putrefaciens, Brochothrix thermosphacta, and Lactobacillus plantarum). The antioxidant assays were carried out for studying the free radical scavenging capacity and the anti-lipoperoxidant activity. The results showed that eugenol and capsaicin were the most active against both pathogens and spoilage bacteria. S. aureus was one of the most affected strains (median concentration of growth inhibition: IC50 eugenol = 0.75 mM; IC50 capsaicin = 0.68 mM; IC50 vanillin = 1.38 mM). All phytochemicals slightly inhibited the growth of L. plantarum. Eugenol was the most active molecule in the antioxidant assays. Only in the oxygen radical absorbing capacity (ORAC) test did vanillin show an antioxidant activity comparable to eugenol (eugenol ORAC value = 2.12 ± 0.08; vanillin ORAC value = 1.81 ± 0.19). This study, comparing the antimicrobial and antioxidant activities of three guaiacol derivatives, enhances their use in future applications as food additives for contrasting both common pathogens and spoilage bacteria and for improving the shelf life of preserved food.

CaO catalyst for multi-route conversion of oakwood biomass to value-added chemicals and fuel precursors in fast pyrolysis

The impact of CaO on oakwood pyrolysis was explored by the Py-GC/MS at 500 °C. Ca(OH)2 presents on the CaO surface, indicating its partial hydration (noted as CaOOH). CaOOH promoted the ketonisation of carboxylic acids to aliphatic ketones, furfural to cyclopentanone/2-cyclopentenone, facilitated the elimination of the methoxy-phenolic compounds. The catalyst loading did not show any significant effect on the formation of acetone, while a noticeable reduction in the phenolics was revealed. Increasing catalyst loading almost eliminated CO2, acids, furans, aldehydes, ether groups, whilst the fractions of alcohols, esters, sugars, and alkoxybenzene decreased noticeably. The use of partially hydrated CaOOH in the CFP can create conditions where by-products generated during the ketonisation and phenolics upgrading reactions (CO2, H2O, CO) interact through the adsorption enhance water-gas-shift reaction and through coking reactions with formation of H2 used for hydrogenation during multistep conversion of furfural to cyclopentanone in a vapour phase.

Optimization of Solid Phase Microextraction (SPME) Coupled with Gas Chromatography Mass Spectrometry (GC-MS) for Fermented Perilla Leaves Jiaosu and Volatile Profiling Analysis During Fermentation

A method based on solid phase microextraction coupled with gas chromatography mass spectrometry was developed for volatile profiling fermented perilla leaves jiaosu (PFJ) during fermentation. Five fibers were firstly evaluated by the total peak areas and the number of volatile compounds. Secondly, a Plackett-Burman design was applied to screen for seven independent variables selected in literature. Three significant variables (extraction time, extraction temperature and equilibrium time) were therefore selected for the following optimization studies. A Box-Behnken design combined with a steepest ascent was then used to optimize the significant factors. Under optimal conditions, the changes of volatile profiles of PFJ at 7, 14, 21, 28, 91 and 140 d were analyzed. A total of fifty-one volatile compounds were identified, and alcohols (68.12–78.94%) were the main volatile components in PFJ, followed by methoxy-phenolic compounds (4.67–5.48%). Perilla alcohol and trans-Shisool were the major constituents during spontaneous fermentation, which accounted for 16.14–30.66% and 19.95–24.52%, respectively. The results showed that PFJ fermented into a health probiotic product with characteristic flavour and functional volatile compounds.

Kinetic and Theoretical Study of the Atmospheric Aqueous-Phase Reactions of OH Radicals with Methoxyphenolic Compounds.

Methoxyphenols, which are emitted through biomass burning, are an important species in atmospheric chemistry. In the present study, temperature-dependent aqueous-phase OH radical reactions of six methoxyphenols and two related phenols have been investigated through laser flash photolysis and the density functional theory. The rate constants obtained were in a range of (1.1-1.9) × 1010 L mol-1 s-1 with k(3-MC) > k(Cre) ≈ k(Syr) ≈ k(MEP) > k(Res) > k(3-MP) > k(2-EP) ≈ k(2-MP). We derived the parameters of these reactions from the obtained T-dependent rate constants and found a mean Arrhenius activation energy of 16.9 kJ mol-1. The diffusion rate constants were calculated for each case and compared to the measured ones. Generally, the rate constants are found to be close to fully diffusion-controlled (kdiff = (1.4-1.5) × 1010 L mol-1 s-1 for all reactions). A structure-function relationship was established through the measurement result, which could be used for predicting unknown rate constants of other phenolic compounds. All of these findings are expected to enhance the predictive capabilities of models, such as the chemical aqueous-phase radical mechanism.

Infrared spectroscopy of secondary organic aerosol precursors and investigation of the hygroscopicity of SOA formed from the OH reaction with guaiacol and syringol.

Attenuated total reflection Fourier transform infrared spectroscopy (ATR-FTIR) synchrotron analyses supplemented by density functional theory (DFT) anharmonic calculations have been undertaken to study the fundamental vibrational signatures of guaiacol and syringol, two methoxyphenol compounds found at the highest concentrations in fresh wood smoke and precursors of secondary organic aerosols (SOA) affecting the radiative balance and chemistry of the atmosphere. Nitroderivatives of these two compounds have also been studied experimentally for nitroguaiacol and theoretically for nitrosyringol. All the active fundamental vibrational bands have been assigned and compared to available gas phase measurements, providing a vibrational database of the main precursors for the analysis of SOA produced by atmospheric oxidation of methoxyphenols. In addition, the SOA formed in an atmospheric simulation chamber from the OH reaction with guaiacol and syringol were analyzed using the ATR-FTIR synchrotron spectroscopy and their hygroscopic properties were also investigated. The vibrational study confirms that nitroguaiacol and nitrosyringol are the main oxidation products of methoxyphenols by OH and are key intermediates in SOA production. The hydration experiments highlight the hydrophilic and hydrophobic characters of nitrosyringol and nitroguaiacol, respectively.

Kinetic Study of the Gas-Phase Reactions of Nitrate Radicals with Methoxyphenol Compounds: Experimental and Theoretical Approaches.

The gas-phase reactions of five methoxyphenols (three disubstituted and two trisubstituted) with nitrate radicals were studied in an 8000 L atmospheric simulation chamber at atmospheric pressure and 294 ± 2 K. The NO3 rate constants were investigated with the relative kinetic method using PTR-ToF-MS and GC-FID to measure the concentrations of the organic compounds. The rate constants (in units of cm(3) molecule(-1) s(-1)) determined were: 2-methoxyphenol (guaiacol; 2-MP), k(2-MP) = (2.69 ± 0.57 × 10(-11); 3-methoxyphenol (3-MP), k(3-MP) = (1.15 ± 0.21) × 10(-11); 4-methoxyphenol (4-MP), k(4-MP) = (13.75 ± 7.97) × 10(-11); 2-methoxy-4-methylphenol, k(2-M-4-MeP) = (8.41 ± 5.58) × 10(-11) and 2,6-dimethoxyphenol (syringol; 2,6-DMP), k(2,6-DMP) = (15.84 ± 8.10) × 10(-11). The NO3 rate constants of the studied methoxyphenols are compared with those of other substituted aromatics, and the differences in the reactivity are construed regarding the substituents (type, number and position) on the aromatic ring. This study was also supplemented by a theoretical approach of the methoxyphenol reactions with nitrate radicals. The upper limits of the NO3 overall rate constants calculated were in the same order of magnitude than those experimentally determined. Theoretical calculations of the minimum energies of the adducts formed from the reaction of NO3 radicals with the methoxyphenols were also performed using a DFT approach (M06-2X/6-31G(d,p)). The results indicate that the NO3 addition reactions on the aromatic ring of the methoxyphenols are exothermic, with energy values ranging between -13 and -21 kcal mol(-1), depending on the environment of the carbon on which the oxygen atom of NO3 is attached. These energy values allowed identifying the most suitable carbon sites for the NO3 addition on the aromatic ring of the methoxyphenols: at the exception of the 3-MP, the NO3 ipso-addition to the hydroxyl group is one of the favored sites for all the studies compounds.

Characterization of Aroma-Active Compounds of Pu-erh Tea by Headspace Solid-Phase Microextraction (HS-SPME) and Simultaneous Distillation-Extraction (SDE) Coupled with GC-Olfactometry and GC-MS

Aroma volatiles from ripened and raw pu-erh tea were extracted by headspace solid-phase microextraction (HS-SPME) and simultaneous distillation-extraction (SDE). They were then characterized and identified using gas chromatography-olfactometry (GC-O) and gas chromatography-mass spectrometry (GC-MS). The conditions of HS-SPME including fiber selections and sampling condition optimization have been previously investigated. With the two methods, 39 and 33 aroma-active compounds were detected and characterized in ripened and raw pu-erh tea samples, respectively. The aroma-active compounds with similar sensory descriptors were grouped into the same category, and the sum of individual aroma intensity values within each category showed that the floral aroma (33.01 %), stale/musty aroma (25.24 %), and woody aroma (11.17 %) were the major aroma categories in ripened pu-erh tea. Alcohols (floral aroma notes), methoxyphenolic compounds (stale/musty aroma notes), and ketones (woody or floral aroma notes) play a vital role in the special flavor of ripened pu-erh tea. In raw pu-erh tea, the floral aroma (38.62 %) and fruity aroma (16.55 %) were the major aroma categories. These aromas were closely related to the characteristics of raw pu-erh tea aroma and its sensory perception.

The study of fingerprint characteristics of Dayi Pu-Erh tea using a fully automatic HS-SPME/GC-MS and combined chemometrics method.

The quality of tea is presently evaluated by the sensory assessment of professional tea tasters, however, this approach is both inconsistent and inaccurate. A more standardized and efficient method is urgently needed to objectively evaluate tea quality. In this study, the chemical fingerprint of 7 different Dayi Pu-erh tea brands and 3 different Ya'an tea brands on the market were analyzed using fully automatic headspace solid-phase microextraction (HS-SPME) combined with gas chromatography-mass spectrometry (GC–MS). A total of 78 volatiles were separated, among 75 volatiles were identified by GC–MS in seven Dayi Pu-erh teas, and the major chemical components included methoxyphenolic compounds, hydrocarbons, and alcohol compounds, such as 1,2,3-trimethoxybenzene, 1,2,4-trimethoxybenzene, 2,6,10,14-tetramethyl-pentadecane, linalool and its oxides, α-terpineol, and phytol. The overlapping ratio of peaks (ORP) of the chromatogram in the seven Dayi Pu-erh tea samples was greater than 89.55%, whereas the ORP of Ya'an tea samples was less than 79.10%. The similarity and differences of the Dayi Pu-erh tea samples were also characterized using correlation coefficient similarity and principal component analysis (PCA). The results showed that the correlation coefficient of similarity of the seven Dayi Pu-erh tea samples was greater than 0.820 and was gathered in a specific area, which showed that samples from different brands were basically the same, despite have some slightly differences of chemical indexes was found. These results showed that the GC-MS fingerprint combined with the PCA approach can be used as an effective tool for the quality assessment and control of Pu-erh tea.

Comparative Analysis of Pu-erh and Fuzhuan Teas by Fully Automatic Headspace Solid-Phase Microextraction Coupled with Gas Chromatography–Mass Spectrometry and Chemometric Methods

Thirteen Pu-erh teas and 13 Fuzhuan teas obtained from two different production areas in China were profiled using fully automatic headspace solid-phase microextraction (HS-SPME)/gas chromatography-mass spectrometry (GC-MS) coupled with chemometric methods. A total of 93 aroma components were identified in 26 dark teas; among them, methoxyphenolic compounds (31.77%) were the most abundant components in Pu-erh teas, whereas ketone compounds were the most abundant components (25.42%) in Fuzhuan teas. Cluster analysis (CA) and principal component analysis (PCA) showed that these two types of dark teas could be clearly distinguished according to their chemical characteristics. This study suggested that the proposed strategy could provide a feasible and rapid technique to differentiate dark teas with similar morphological characteristics from different production areas by their volatile composition and relative content.

Characterization of volatile compounds of pu-erh tea using solid-phase microextraction and simultaneous distillation–extraction coupled with gas chromatography–mass spectrometry

Two extraction methods, namely, solid-phase microextraction (SPME) and simultaneous distillation–extraction (SDE) both followed by gas chromatography–mass spectrometry were applied for the determination of a wide range of volatile compounds in pu-erh tea. The conditions of solid-phase microextraction including fiber selections and sampling condition optimization have been previously investigated. By the two methods, 79 volatile compounds belonging to different categories were identified. Among them, 61 volatile compounds were extracted by SDE and 67 by SPME. Qualitative and quantitative differences of pu-erh tea volatile profiles were observed by applying the two aforementioned extraction methods. SDE technique achieved higher percentages of high molecular weight alcohols, acids, and esters of low volatility, whereas SPME technique was found useful for analyzing low molecular weight alcohols, methoxy-phenolic compounds, aldehydes, ketones, and hydrocarbons of high volatility that were closely related to the characteristics of pu-erh tea aroma and its sensory perception. Therefore, SPME technique was a reliable extraction method for controlling pu-erh tea quality flavor.

Optimization of Headspace Solid-Phase Microextraction Coupled with Gas Chromatography–Mass Spectrometry for Detecting Methoxyphenolic Compounds in Pu-erh Tea

A method based on headspace solid-phase microextraction coupled with gas chromatography-mass spectrometry was developed for the analysis of volatile methoxyphenolic compounds in pu-erh tea. Six fibers with different polarities were initially evaluated. The 75 μm carboxen/polydimethylsiloxane fiber exhibited the highest extraction efficiency and was selected for further optimization. A Plackett-Burman design was used to screen for the brewing proportion of tea and water, amount of pu-erh tea, ionic strength, extraction time, extraction temperature, desorption time, rate of agitation, and equilibrium time. A Box-Behnken design was then applied to optimize the significant factors. Under optimal conditions, the proposed method affords a wide range of linearity, high linear regression coefficients (0.996-0.999), less than 9.0% repeatability of relative standard deviation, and limits of detection ranging from 2.31 to 21.80 ng/g. The proposed method has satisfactory accuracy, with recoveries of 79.08-113.9%. This method was successfully applied for the analysis of pu-erh tea samples.

Anti-inflammatory effects of methoxyphenolic compounds on human airway cells

BackgroundThe respiratory epithelium plays a central role in the inflammatory response in asthma and other diseases. Methoxyphenolic compounds are purported to be effective anti-inflammatory agents, but their effects on the airway epithelium have not been well characterized.MethodsHuman airway cells were stimulated with TNF-α in the presence or absence of 4-substituted methoxyphenols and resveratrol. The expression of various cytokines was measured by qPCR, ELISAs, and protein arrays. Reactive oxygen species (ROS) production was measured with a reactive fluorescent probe (3',6'-diacetate-2',7'-dichlorofluorescein). Activation of NF-κB was measured by nuclear translocation and phosphorylation. Ribonuclear protein association with mRNA was assessed with a biotin-RNA affinity isolation assay.ResultsMultiple inflammatory mediators were inhibited by methoxyphenols, including: CCL2, CCL5, IL-6, IL-8, ICAM-1, MIF, CXCL1, CXCL10, and Serpin E1. IC50 values were obtained for each compound that showed significant anti-inflammatory activity: diapocynin (20.3 μM), resveratrol (42.7 μM), 2-methoxyhydroquinone (64.3 μM), apocynin (146.6 μM), and 4-amino-2-methoxyphenol (410 μM). The anti-inflammatory activity did not correlate with inhibition of reactive oxygen species production or NF-κB activation. However, methoxyphenols inhibited binding of the RNA-binding protein HuR to mRNA, indicating that they may act post-transcriptionally.ConclusionsMethoxyphenols demonstrate anti-inflammatory activity in human airway cells. More potent compounds that act via similar mechanisms may have therapeutic potential as novel anti-inflammatory agents.

Aroma characterisation of Pu-erh tea using headspace-solid phase microextraction combined with GC/MS and GC–olfactometry

Volatile compounds from Pu-erh tea were extracted using a headspace-solid phase microextraction (HS-SPME), and analysed with a gas chromatography–mass spectrometry (GC–MS) and a gas chromatography olfactometry (GC–O). Results showed that a total of 66 major volatile compounds were identified by GC–MS analysis; among them, methoxy-phenolic compounds (33.58%), alcohols (23.01%) and hydrocarbons (11.62%) were the major chemical classes. It was found that 1,2,3-trimethoxybenzene (17.16%) was the most abundant aroma components, followed by α-terpineol (5.68%), 1,2-dimethoxybenzene (4.64%) and linalool oxide II (4.29%) in order. Twenty-nine odour active compounds were perceived by GC–O analysis. Further investigation showed that 1,2-dimethoxybenzene, 1,2,3-trimethoxybenzene, 1,2,3-trimethoxy-5-methylbenzene, 4-ethyl-1,2-dimethoxy-benzene, β-ionone, β-linalool, linalool oxides, decanal, etc. were responsible for the special flavour in Pu-erh tea. It seems that the methoxy-phenolic compounds and alcohols play a vital role in the special flavour of Pu-erh tea.

Headspace-single drop microextraction (HS-SDME) in combination with high-performance liquid chromatography (HPLC) to evaluate the content of alkyl- and methoxy-phenolic compounds in biomass smoke

The content of ten phenolic compounds present in four different biomass smoke materials: rock rose (Cistus monpelienisis), prickly pear (Opuntia ficus indica), pine needles (Pinus canariensis), and almonds skin (Prunus dulcis), have been evaluated. The sampling method mainly consisted of a trap alkaline solution to solubilize the phenols, and was optimized by an experimental design. Average sampling efficiencies of 78.1% and an average precision value of 10.6% (as relative standard deviation, RSD), were obtained for the selected group of phenols. The trapped phenolates were further analyzed by a headspace-single drop microextraction (HS-SDME) procedure, in combination with high-performance liquid chromatography (HPLC) with UV detection. The optimum variables for the HS-SDME method were: 1-decanol as extractant solvent, 3.5μL of microdrop volume, 2mL of sample volume, a pH value of 2, saturation of NaCl, an extraction temperature of 60°C, and an extraction time of 25min. The optimized HS-SDME method presented detection limits ranging from 0.35 to 5.8μgmL−1, RSD values ranging from 0.7 to 7.4%, and an average relative recovery (RR) of 99.8% and an average standard deviation of 5.2. The average content of phenolic compounds in the biomass materials studied were 70, 161, 206 and 252mgkg−1 of biomass for prickly pear, almonds skin, rock rose, and pine needles, respectively. The main components of the smokes were vanillin, phenol and methoxyphenols, in all smoking materials studied.

Dietary phenolic acids attenuate multiple stages of protein glycation and high‐glucose‐stimulated proinflammatory IL‐1β activation by interfering with chromatin remodeling and transcription in monocytes

This study examined the effects of dietary phenolic acids on individual stages of protein glycation and utilized monocyte cultures to assess whether these phytochemicals modulate the activation of proinflammatory cytokine under high glucose (HG, 15 mmol/L) conditions mimicking diabetes. In vitro glycation assays showed that a number of phenolic acids exerted inhibitory effects on the glycation reaction and its subsequent crosslinking. Phenolic acids, especially methoxyphenolic acids, prevented increase in both levels of the interleukin-1beta (IL-1beta) and oxidative stress caused by HG. The effect appeared to be mediated by modulation of the protein kinase C/nuclear factor-kappaB axis. Chromatin immunoprecipitation demonstrated for the first time that HG increased the recruitment of nuclear factor-kappaB p65 and CREB-binding protein to the IL-1beta promoter. Interestingly, HG also increased histone acetylation and methylation within the IL-1beta promoter and decreased histone deacetylase activities in monocytes, thus facilitating chromatin remodeling and transcription. Such inappropriate inflammatory responses were found to be controlled effectively by treatment with methoxyphenolic compounds. In conclusion, this study suggests that phenolic acids could exert their anti-inflammatory activities as antiglycation agents and as modifiers of signaling pathways. It provides evidence for a novel mechanism by which phenolics supplementation might have additional protective effects against diabetic complications.

Optimization of an analytical methodology for the determination of alkyl- and methoxy-phenolic compounds by HS-SPME in biomass smoke

A sampling and analysis method for the determination of 21 phenolic compounds in smoke samples from biomass combustion has been developed. The smoke is used to make smoked foods, following an artisanal procedure used in some parts of the Canary Islands. The sampling system consists of a Bravo H air sampler, two impingers, each one containing an aqueous solution of sodium hydroxide 0.1 mol L(-1), followed by a silica gel trap. The variables optimized to reach the best sampling conditions were volume of absorbent solution and sampling flow. Under the optimum conditions, 100 mL of absorbent solution of NaOH 0.10 mol L(-1) and 2 L min(-1) for the sampling flow, sampling efficiencies are higher than 80%. Analysis of phenolic compounds was carried out by headspace solid-phase microextraction (HS-SPME) coupled to gas chromatography-mass spectrometry (GC-MS). Five different fiber coatings were employed in this study. By means of a central composite design, extraction time, salt concentration, and pH of the solution were optimized: 65-microm carbowax-divinylbenzene, extraction time 90 min, concentration in NaCl of 35% (m/v), and pH 2 yielded the highest response. Detection limits of phenol and their alkyl derivatives, guaiacol and eugenol, are between 1.13 and 4.60 ng mL(-1). 3-Methoxyphenol, 2,6-dimethoxyphenol, and vanillin have detection limits considerably higher. Good linearity (R2 > or = 0.98) was observed for all calibration curves in the established ranges. The reproducibility of the method (RSD, relative standard deviation) was found to oscillate between 7 and 18% (generally close or lower than 10%).

Identification and application of a new fungal strain Bjerkandera adusta R59 in decolorization of daunomycin wastes

A strain of an anamorphic fungus, morphologically similar to Geotrichum candidum Link ex Leman was isolated from a soil sample. The fungus was identified on the basis of the ITS region analysis as basidiomycete Bjerkandera adusta (Willd. ex Fr.) P. Karst. The strain exhibited interesting properties, in particular, the capacity for decomposing of anthracyclic antibiotics (daunomycin)—very uncommon feature among fungi. Daunomycin decolorization performed by this fungus seemed to be a process of secondary metabolism (idiophase), accompanied by an increase of peroxidase activity and decrease of methoxyphenolic compounds and free radicals levels. Rate of the antibiotic degradation depended on its concentration. The strain adapted to growth on crude daunomycin effluent decomposed it more effectively than the fungus before adaptation.